I am running Vista and FF 48.0.1. I have been successfully installing addons (they are listed and enabled) (I've also removed and reinstalled) but they are not in the toolbar or under Customize Additional Tools and Features. I'm a somewhat seasoned user but not anywhere near a developer's expertise. My toolbars are pretty full but are not showing any arrows to reveal more addons. If anyone out there can help I would be most grateful. I would just hate to have to start from scratch. Thanks again. Sharon in Allentown, PA